The collaborative project "Light Budget" aims at prioritizing building strategies and techniques that allow the best ratio between lighting benefits and CO2 emissions.
The construction sector accounts for 40% of global greenhouse gas (GHG) emissions. It is therefore essential to better understand the industrial issues behind the climate transition. In this context, natural lighting, which is mainly conditioned by the technical and architectural choices of the building envelope, can be seen as a comfort imperative in construction. However, facades not only play a central role in managing this parameter but are also responsible for more than a quarter of a building's GHG emissions. The structural part holds the major impact of the façade, followed by the exterior cladding, the insulation, the glass, the blind system, and the frame.
Light Budget is a collaborative project seeking to determine target carbon budgets at the scale of the facade components in order to identify construction techniques that could be compatible with climate neutrality. These budgets per component can also be used by manufacturers as target objectives so that their products remain competitive on the low-carbon market. They will set a course for their R&D to orient future developments towards products that will be prescribed on tomorrow's market, which will be subject to increasing constraints.
The developed co-simulation platform establishes the evaluation of the carbon impact over the whole life cycle, as well as the natural light contribution. The first results of the simulations have been used to create a knowledge database on facades with 3840 facade variants. The exploration of this database is possible with statistical analyses as well as interactive graphical representation tools.
The project results provide a snapshot of current facade construction practices, compare them to climate targets, and measure the step that must be taken to remain competitive in the race for low-carbon products and buildings. Target carbon budgets at the scale of the facade components allow to identify the construction techniques that could contribute to attaining climate neutrality. The increase in skills for the partners, and more broadly for the actors of the construction industry, on the subject of the evaluation of the carbon footprint of construction products and buildings is a complementary objective, central as well for the collaborative project.